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February 6, 2010, 11:19 am

AutomotiveForums M

Question: What could be causing the engine to be idling rough?

2002 Chevy Trailblazer running rough when idling, especially when its cold and it sometimes hesitates. The engine sounds like it is missing. Thought it was because I got some bad gas but still having the problem.I have replaced the fuel filter, spark plugs, ignition coil #2,4,and 6 and 2 yrs ago I replaced the throttle position sensor. When i replace the fuel filter i notice the gas that came out of it was very dirty. I have also used the fuel injector cleaner a few times when I filled up with gas.

February 14, 2012, 2:45 pm

AutomotiveForums M

Sounds like you may need to check the remaining coil packs. Go to your local Autozone or Advanced Auto Parts and let the hook it up to there diagnostic computer. This will narrow down which coil pack it is. (It is also free of any charge) My 2002 Trailblazer was doing the same thing and I did the diagnostic check on it, it replied the code PO301 which is Cylinder #1 misfire. Cylinder 1 is the very first cylinder if you have the in-line 6 cylinder. I was told that for some reason it usually is the first coil to go bad, for what ever reason I don't know. But after I replaced mine it ran like a champ. I hope this helps. Good luck.

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